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Wet duct

Hopefully this doesn't tread too far toward DIY territory, but
I've got a little problem with a cold-air intake that someone
might have some insight into. You guys must deal with
fresh-air inlet ducts in some fashion once in a while...

This is the inlet to an HRV, and is a piece of PVC pipe
that comes in through a sealed wall penetration. It's
PVC instead of metal to avoid thermal bridging to outside,
but it's still passing cold air so the whole pipe is
naturally going to get a little chilly. It connects
immediately to a piece of insulated 6" flex that runs
right down into the HRV inlet. In the original setup,
the outer jacket + fiberglass of the flex was snugged
up around the PVC pipe tight to the wall, to try and not
expose any of the cold bits. Last night I discovered
that air circulation around that area had nonetheless
caused condensation to form in the end of the fiberglass
and start soaking down into the flex duct *and* into
the wood of the wall that the pipe passes through.

When y'all do a fresh-air duct penetration for cold
climates, how do you prevent condensation problems
on the inside??